Pressure relief mechanism

ABSTRACT

A pressure relief mechanism for the work rolls in a rolling mill strand with a frame in which a holddown device exerts the desired pressure on the work rolls. The relief mechanism includes a plurality of disc-shaped members with opposing projections positioned between the holddown device and the work rolls. The projections of the members can be placed in more or less register to vary the pressure between the work rolls. Excessive pressure on the work rolls is relieved by moving at least one of the members relative to the other to intermesh their projections, thereby allowing limited vertical movement of one of the work rolls to relieve pressure between the rolls.

United States Patent Primary ExaminerMilton S. Mehr Attorney-Mason,Mason & Albright ABSTRACT: A pressure relief mechanism for the workrolls in a rolling mill strand with a frame in which a holddown deviceexerts the desired pressure on the work rolls. The relief mechanismincludes a plurality of disc-shaped members with opposing projectionspositioned between the holddown device and the work rolls. Theprojections of the members can be placed in more or less register tovary the pressure between the work rolls. Excessive pressure on the workrolls is relieved by moving at least one of the members relative to theother to intermesh their projections, thereby allowing limited verticalmovement of one of the work rolls to relieve pressure between the rolls.

PATENTEDJAN 4m 3.631. 696

WILLARD a. wlullms FIG. 3

PRESSURE RELIEF MECHANISM This invention relates to a quick release in arolling mill stand which allows vertical movement of one working rollrelative to the other roll to prevent damage to the work roll whenwrecks occur during rolling operation. The device can also be used inpresses and related machinery. When cobbles or doubling up occurs insteel sheets or plates being rolled at high speed, the pressure betweenthe work rolls becomes excessive and if not quickly relieved, permanentdamage is done to the rolling equipment, particularly to the expensivework rolls. Ordinarily, the beginning of a wreck usually does not dogreat damage, but as the steel sheet or plate doubles and redoubles andpasses between the work rolls, the pressure increases, causing greatheat, distortion and fire cracking of the rolls.

Thus, the present invention is not intended to prevent wrecks, but toprevent damage ultimately done to the rolling equipment involved inwrecks. In particular, this invention is a quick release for pressureapplied to the work rolls, permitting the rolls to separate by verticalmovement before damage oc curs. The quick release device can beassociated with a screwdown on the work rolls or with work rollspressurized by a hydraulic system. The device can be kicked off" by aconventional monitoring system in which an electric monitor, such as aphotoeye, detects distortions in the steel being processed, and switchesa motor to move a rod, gear or other mechanism associated with thequick-release device. The device can also be associated associated witha press ductor that mounts under each side of the lower backup roll toconstantly monitor the roll pressure. With this arrangement, an instantsignal is made by an amplifier, when pressure exceeds a predeterminedlevel. Such monitors are well known and form no part of this invention,apart from the combination disclosed herein.

Once the monitor is activated, a first part of the device is movedrelative to a second part and projections between the two parts areplaced in more or less register to vary the vertical distance betweenthe parts and ultimately, the spacing between the work rolls.

It is therefore an object of the present invention to provide aquick-release device that can be associated with the structure thatexerts pressure on the work rolls of a roll stand, to quickly andeffectively relieve excessive pressure between the rolls therebypreventing damage to same when wrecks occur during operation.

These and other objects will be apparent from the description anddrawings in which:

FIG. 1 is a side elevation of the mill stand showing a frame with rollsin work position and the relative location of the quick release device.

FIG. 2 is an enlarged perspective view of the quick release device inwork position.

FIG. 3 is a perspective view of the FIG. 2 device after kickoff.

FIG. 4 is a plan view showing the configuration of the quick releasedevice.

In FIG. 1, the rolling mill stand includes a frame 1 in which slideablelower roll chock 3 and upper chock 5 are mounted to move lower backuproll 7 and upper backup roll 9 respectively relative to each other invertical directions. Backup rolls 7 and 9 bear on work rolls 1] and 13respectively and the work rolls are mounted in chock blocks 11A and 13Awhich are slideable vertically relative to one another in lower rollchock 3.

Lower chock 3 can be permanently affixed in the lower part of frame 1 orbe slideably mounted as shown in FIG. 1 with adjusting bolts 17 and 19having threaded nuts 21 and 23 to fix chock 3 in its selected position.Another conventional arrangement would be the use of hydraulic pistonsin place of bolts 17 and 19 to adjustably position the lower chock.

The upper chock roll 5 is held down by conventional hydraulic means or ascrewdown as seen in FIG. 1 Between the holddown l5 and chock 5 apressure quick-relief device 30 is positioned to include an upper member29 and a lower member 31 which can each be disc shaped. The lower member31 is preferably keyed at 33 to the roll chock 5 and fixed in place. Theupper member 29 is movable relative to member 31 and is preferablytumable about a dowel or pin 35 which is fitted in the approximatecenters of the disc members 29 and 31.

Each of the disc members have projections 37 and 39 which can begenerally teethlike in configuration so that opposing projections can beplaced in more or less register with one another and thereby decrease orincrease the pressure that holddown l5 exerts on working roll 11. Theteeth 37 and 39 could take the form of inclined planes of variousconfigurations so long as the projections can interfit upon kickofif Asseen in FIGS. 1 and 2, the teeth crowns 37A of projections or teeth 37on upper member 29 oppose the crowns 39B of teeth 39 on lower member 31when the mill stand is operating and in work position. The crowns 37Aand 39A can be flattened to provide more surface friction therebyresisting the displacement of the disc members relative to one another.Displacement of the member 29 for its position in FIGS. 1 and 2 can onlytake place in one direction, namely, counterclockwise as shown in thedrawings, since bumper stops 4] and 43 of the lower and upper membersrespectively, prevent contramovement when in abutment.

In the embodiment shown, the disc members 29 and 31 are held together bythe pressure exerted by holddown 15 and are held in alignment with eachother by pin 35. The longitudinal axis of pin 35 is substantiallyvertical and normal to the longitudinal axes of the work rolls 11 and13. The disc members 29 and 31 are of metal and can be about 4 or 5inches thick and 15 inches in diameter with projections 37 and 39 eachabout one-fourth inch in height. The crowns 37A and 39A can have flatspots about I inch long with centers about 6 inches apart so that foreach 3 inches of lineal movement of the outer edge of member 29 relativeto fixed member 31, about onefourth inch of vertical movement can begained by the upper roll chock 5 and, consequently, work roll 11. Itwill be appreciated that the above dimensions can be varied to suitparticular needs and that the provision of flat spots 37A and 39A ispreferred, not mandatory. Also, tapered roller bearings can be mountedon the fiat spots to vary the friction resistance encountered when onemember turns relative to the other member.

In general, about one-eighth or three-sixteenth inch of verticalmovement of one of the work rolls will suffice to relieve the excessivepressure that would otherwise damage the rolls when cobbles or doublesoccur in most steel sheet or plate being rolled.

The upper disc member 29 can be turned or kicked off to relieve pressureby means of a rod 47 which bears on a flat segment 45 positioned at aright angle to the axis of pin 35. Rod 47 is preferably hydraulicallyactuated by a system (not shown) that has an electric switch responsiveto the detection of cobbles, doubles and other deformaties that causewrecks. The hydraulic system is preferably double action so that themember 29 can be returned to mill run position.

It will be understood that the lower disc member 31 or both members 29and 31 can be moved responsive to hydraulic or other devices so as tointermesh teeth 37 and 39 and relieve excessive pressure. Also, morethan two disc members or a thrust-bearing device can be used so long asthe movement of projections serve to decrease the distance betweenopposing members and allow vertical movement of the work rolls withrespect to one another.

I claim:

1. A pressure relief mechanism for a rolling mill stand comprising aframe with work rolls that are vertically displaceable relative to oneanother within said frame and a holddown for urging said work rollsagainst one another at the desired rolling pressure, a quick releasedevice located between one of said work rolls and said holddown, saiddevice including two juxtaposed members having opposing teeth means, thefirst of said members being turnable relative to the second of saidmembers about a pin, responsive to a force exerted substantially normalto the axis of said pin, whereby the teeth means of said members can beplaced in more or less register with one another to vary the pressurebetween the said work rolls.

2. The mechanism of claim 1 wherein said members have abutting stopmeans to limit the relative turning movement of said members in onedirection.

3. The mechanism of claim 2 wherein said teeth means comprises aplurality of teeth that have flat portion at their crowns whereby theopposing crowns of said teeth means are in pressure contact with oneanother when said stop means limits the relative movement of saidmembers in one direction.

4. The mechanism of claim 1 wherein said members are disc shaped andsaid first member is turnable relative to said second member, said firstmember having a flat segment normal to the axis about which said firstmember turns.

5. The mechanism of claim 4 wherein the first of said memhers ispositioned above the second of said members and the latter is affixed toa chock in which a backup roll is mounted to exert pressure on the upperof said work rolls.

6. The mechanism of clam 5 wherein the holddown is a screwdown which isthreaded on said frame to bear on said chock.

7. The mechanism of claim 1 wherein the longitudinal axis of said pin issubstantially vertical and at right angles to the longitudinal axis ofthe work rolls.

8. The mechanism of claim I wherein said teeth means comprises aplurality of teeth with opposing crowns having flat portions in pressurecontact during operation, the centers of adjoining crowns on one memberbeing spaced apart a distance about six times the lengths of said flatportions.

1. A pressure relief mechanism for a rolling mill stand comprising aframe with work rolls that are vertically displaceable relative to oneanother within said frame and a holddown for urging said work rollsagainst one another at the desired rolling pressure, a quick releasedevice located between one of said work rolls and said holddown, saiddevice including two juxtaposed members having opposing teeth means, thefirst of said members being turnable relative to the second of saidmembers about a pin, responsive to a force exerted substantially normalto the axis of said pin, whereby the teeth means of said members can beplaced in more or less register with one another to vary the pressurebetween said work rolls.
 2. The mechanism of claim 1 wherein saidmembers have abutting stop means to limit the relative turning movementof said members in one direction.
 3. The mechanism of claim 2 whereinsaid teeth means comprises a plurality of teeth that have flat portionsat their crowns whereby the opposing crowns of said teeth means are inpressure contact with one another when said stop means limits therelative movement of said members in one direction.
 4. The mechanism ofclaim 1 wherein said members are disc shaped and said first member isturnable relative to said second member, said first member having a flatsegment normal to the axis about which said first member turns.
 5. Themechanism of claim 4 wherein the first of said members is positionedabove the second of said members and the latter is affixed to a chock inwhich a backup roll is mounted to exert pressure on the upper of saidwork rolls.
 6. The mechanism of claim 5 wherein the holddown is ascrewdown which is threaded on said frame to bear on said chock.
 7. Themechanism of claim 1 wherein the longitudinal axis of said pin issubstantially vertical and at right angles to the longitudinal axis ofthe work rolls.
 8. The mechanism of claim 1 wherein said teeth meanscomprises a plurality of teeth with opposing crowns having flat portionsin pressure contact during operation, the centers of adjoining crowns onone member being spaced apart a distance about six times the lengths ofsaid flat portions.